1. Field of the Invention
This invention relates to brake rotors for use in motor vehicles. More particularly, the present invention relates to a brake rotor having flow through ventilation cooling ducts.
2. Disclosure Information
Ventilated brake rotors used in disc brake assemblies are well known in the automotive brake art for improving the heat transfer to the ambient air. Heat is generated in the brake rotor as the kinetic energy of the moving vehicle is converted to heat energy through the frictional interface between brake pads forcibly applied against the brake rotor. One problem presented in managing the heat generated is preventing warping or coning of the brake rotor. Unequal temperature distribution in the brake rotor between rubbing surfaces leads to thermal stresses which may distort the brake rotor, known as warping and coning. Customers recognize these conditions through either increased brake pedal travel, or roughness felt in the brake pedal under moderate braking.
Another problem related to heat management in brake rotor design is controlling the rubbing surface temperature. As the temperature in the brake rotor increases during repetitive heavy stopping, the frictional properties at the brake interface diminishes above a predetermined temperature. Additionally, preventing the rubbing surfaces from exceeding a predetermined temperature also provides greater durability for the brake rotor.
Finally, heat management has been one of the primary obstacles to designing a successful brake rotor constructed from a lower density material than cast iron or steel. The most suitable materials require a brake rotor design having rubbing surfaces which operates at a significantly reduced temperature range. Additionally, due to the increased thermal conductivity of the lower density materials, excessive heat may be conducted into the hub assembly of the vehicle to which the brake rotor is attached.
It is desirable to design a brake rotor having equal heat distribution to prevent warping or coning of the brake rotor. It also is desirable to design a brake rotor with greater heat transfer efficiency permitting lower operating temperatures at the rubbing surfaces of the brake rotor. Finally, it is desirable to provide a brake rotor design having sufficient heat management to permit the use of a low density material without transferring excessive heat into the hub assembly of the motor vehicle to which the brake rotor is fastened.